Textile laundering is increasingly concerned with the delivery of benefits as well as cleaning. A long lasting fragrance on the dried laundry is one such benefit others include malodour counteractants as illustrated in U.S. Pat. No. 5,554,588, aromatherapy agents, chemaesthetic agents etc. Unfortunately it is technically difficult to achieve both a high degree of cleaning and delivery of small organic molecules to a surface simultaneously as can be seen from the various means which have been attempted to deliver a long lasting fragrance from a laundry cleaning process, e.g. in U.S. Pat. No. 5,500,154. Not only are fragrance ingredients susceptible to reaction with other ingredients in the detergents, they can also be solubilised by surfactant and so lost from the wash. Furthermore volatile materials such as fragrances can evaporate as the laundry dries. Whilst it may be beneficial to generate a noticeable fragrance during the laundering process and while drying, the loss of perfume usually means that comparatively little fragrance remains on the dried laundry.
Adding fragrance during later stages of the laundry process is one way to provide fragrance to the laundry e.g. through rinse conditioners or drier sheets as shown in U.S. Pat. No. 4,511,495 and ironing products but this involves the cost and inconvenience of purchasing and using an additional product. Another method for delivering perfume to laundered fabric is one which increases deposition during the wash and prevents evaporation during drying for example by the use of pro-fragrances. These molecules deposit onto textiles during the wash and later react to release volatile fragrance molecules. The reaction can be triggered by a number of means: under the influence of co-deposited enzymes as in U.S. Pat. No. 5,726,345, of sunlight as in U.S. Pat. No. 6,218,355, or by bacterial or enzymatic decomposition. Such technology is successful but is limited to a relatively small range of fragrance materials which can be used to synthesis pro-fragrances and that the resulting odour cannot comprise the mixture of molecules that generally comprise a full fragrance. A more promising approach has been to encapsulate the fragrance. U.S. Pat. Nos. 4,145,184 and 4,234,627 teach using a capsule with an outer coating which prevents diffusion of the perfume through the capsule wall. The capsules deposit on the fabrics during laundering and open to release their contents as occurs during fabric manipulation. However there are several practical difficulties to be overcome to make this technology work commercially. One of the major difficulties has been to dose the capsules in such a way that they do not separate within the packet of powder because of particle size differences. Also the capsules must be sufficiently robust to withstand all the processes involved in manufacture e.g. transporting, handling and packing yet still be sufficiently friable as to rupture under relatively gentle conditions whilst handling the garment. Thus, it would be desirable to provide a means of protecting a wide range of perfumery materials during prolonged storage in the detergent. For example certain fragrance components are sensitive to the alkalinity and/or bleach content of detergent powders.
It would be desirable to provide a method for delivering a broad range of perfumery ingredients to laundry from a detergent product during the laundry process.
It would be desirable to provide a long lasting fragrance to dried laundry.
It would be desirable to reduce the amount of post tower addition of perfume oil for laundry detergents, which can lead to poor powder properties, and sometimes overly intense fragrance.
It would be even more desirable that any capsule intended to provide the benefits stated above could be in a form so as to mix easily and uniformly in a detergent powder and withstand processing and manipulation during manufacture and yet be capable of rupturing on handling the laundry.